It is clear that in normal English usage _dialect_ means a less
important linguistic variety than does _language_, but what is not
clear to me is (a) whether _dialect_ is really in any way pejorative,
(b) whether possessing a writing system is what defines _language_
or (c) whether people who use _dialect_ and _language_ this way
think of _dialects_ as varieties of some _language_ or not. I think
not, which would mean that when nonlinguists read works that mention
somehing about dialects, they are probably systematically misinterpreting
the information.
It is also an interesting question whether we as linguists should
stop using dialect in its technical sense in order to do away with
the confusion, much as many linguists have stopped using _informant_.

With regard to P Daniels' message on the dialect/language distinction, I've
got a few interesting responses, all confirming a connection between the
distinction and the written/unwritten distinction, but tracing modern
distinctions from the Renaissance. Considering German, Koelle, for example,
writing about African "Sprachen", the 19th c German linguistic term for
"dialect" was "Mundart" (literally "mouth-type"), a direct reference to
speech rather than writing. Modern German linguists generally use the loan
form "Dialekt", as I found out by using the term "Mundart", and was told it
sounds old-fashioned and quaint, as if I was imitating Hermann Paul or one
of those guys. I also think that at least in the 19th c, the German lexical
distinction Sprache (itself related to "speech" cf. sprechen "speak) vs.
Mundart had different connotations (or implications) from current English
"language/dialect" (both "foreign" terms in that they are not Germanic in
origin, cntr. English "tongue" or "speech"). Given German nationalism and
drive toward unity in the 19th c, Mundart seems to have had a particular
Romantic sentimental value among linguists, as a relection of "folkdom".
Koelle, then, would be using a more neutral term with Sprache, avoiding
connotations that might attribute the kind of political or cultural
consciousness to speakers of African languages that would (I think)
occur to Germans hearing that word in his time. (For similar reasons
Africans and other peoples whose political organisation was disdained or
ignored would be described as organised into "tribes" rather than
"nationalities" or post-1960s "ethnic groups". Swahili, of course, uses
the Arabic word "kabila" for "tribe" or "nationality" whether for Africans
or such European distinctions as French, German, etc. -- and also for
different "brands" e.g., of shirts or canned goods.
Apart from that, throughout recorded European history, and certainly in
England, there have been scholars and amateurs interested in particular
dialects (or "local speech varieties") for antiquarian purposes, as
part of an interest in history. This is no doubt the origin of the
dialect societies as linguistics progressed, and esp. after Jones'
insight (also contested as being earlier than him) about the manner
in which dialects are related to each other historically. Historical
linguistics is still driven by the hope of recovering cultural history --
for the most part and by most devotees, cf. even such far-ranging things
as Proto-World, but more interestingly, the branches from it. Or
Nostratic, as opposed to "Their-stratic" (get it? Nostra "our" vs. "their.
Of course I realise that I've metanalysed the str part of "nostra" -- for
English metrical purposes )
Plug-ins in historical linguistics to general linguistic theory still
strike me as less compelling, although in fact my own interests in it are
closer to that. My impression is that historical linguistics will survive
as a branch of linguistics mainly because of its claims on implications
for cultural reconstruction --or maybe I should say it will interest non-
linguists and be tolerated as a legitimate field of inquiry for that
reason. Quite apart from viscerally conditioned negative feelings toward
certain dialects, in the popular mind, there is great interest in dialects
(whatever word is used to refer to them) and explanations based on the
origin of the speakers, akin to substratal theories in linguistics, and/or
the ideas about "they still speak Elizabethan English in ...." The
latter got transmuted after the acceptance of genetic linguistics into a
tool for reconstruction during the 19th c in the realization that earlier
forms sometimes (in fact, often) survive in some spoken dialects but not
in written forms of the language. Therefore, dialects must be systematically
investigated in order to reconstruct "the language" before it
was written. This gave rise to dialectology in the 19th c, along with
the other scientific concern of trying to locate the place of origin and
manner of spread of recognized innovations, esp sound changes, cf. the
Rhenish fan for the second German(ic) consonant shift.
I am convinced that the respect for "dialects" that linguists at least pay
lip service to descends from respect for archaism in dialects at a time
when ancestor worship for purposes of political unification was rampant,
esp in Germany in the 19th c. And, like it or not, 19th c German thinking
in historical linguistics is THE most important strand in the formation of
current linguistics, obviously with changes in rationalisation of why
the dialect/language distinction is interesting and "important". Benji